Process for converting a hydrocarbon feed and apparatus relating thereto

ABSTRACT

The embodiments disclosed herein can provide a process for converting a hydrocarbon feed. The process may include hydrocracking the hydrocarbon feed slurried with a particulate catalyst in a presence of hydrogen in a hydrocracking reaction zone to produce a hydrocracked stream, separating at least a portion of the hydrocracked stream, and passing the at least the portion of the hydrocracked stream through a thermal cracking heating zone at conditions effective for thermally cracking the at least the portion of the hydrocracked stream.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Division of copending application Ser. No.13/244,083 filed Sep. 23, 2011, the contents of which are herebyincorporated by reference in its entirety.

FIELD OF THE INVENTION

This invention generally relates to a process for converting ahydrocarbon feed, and an apparatus related thereto.

DESCRIPTION OF THE RELATED ART

Generally, slurry hydrocracking is a useful process and can obtain avery high conversion of various heavy hydrocarbons, such as a vacuumresidue, to desired products that may be further processed to gasolineand/or diesel. However, slurry hydrocracking has a shortcoming, namelyan inadequate conversion of certain heavy hydrocarbons, such as a vacuumgas oil. Usually, refineries require a low capital cost solution tomaximize production of gasoline and diesel from lower value VGO and VR.As a consequence, there is desire to modify a slurry hydrocrackingprocess for converting VGO economically and efficiently.

SUMMARY OF THE INVENTION

The embodiments disclosed herein can provide a process for converting ahydrocarbon feed. The process may include hydrocracking the hydrocarbonfeed slurried with a particulate catalyst in a presence of hydrogen in ahydrocracking reaction zone to produce a hydrocracked stream, separatingat least a portion of the hydrocracked stream, and passing the at leastthe portion of the hydrocracked stream through a thermal crackingheating zone at conditions effective for thermally cracking the at leastthe portion of the hydrocracked stream.

Another exemplary embodiment may be a process for converting ahydrocarbon feed. The process can include hydrocracking the hydrocarbonfeed slurried with a particulate catalyst in a presence of hydrogen in ahydrocracking reactor to produce a hydrocracked stream, separating atleast a portion of the hydrocracked stream in an atmosphericfractionation column to obtain a one or more C20-C50 hydrocarbons streamand a vacuum fractionation column to obtain a one or more C20-C40hydrocarbons stream, and passing the one or more C20-C40 hydrocarbonsstream through a thermal cracking heater at conditions effective forthermally cracking the at least the portion of the hydrocracked streamand providing at least a portion of a product stream to the atmosphericfractionation column.

A further exemplary embodiment can be an apparatus for thermal crackingone or more hydrocarbons. The apparatus can include a slurryhydrocracking zone for receiving a hydrocarbon feed and a particulatecatalyst, a first fractionation zone for receiving a hydrocracked streamfrom the slurry hydrocracking zone, a second fractionation zone forreceiving a one or more C20-C50 hydrocarbons stream from the firstfractionation zone, and a thermal cracking heating zone for receiving aone or more C20-C40 hydrocarbons stream. Typically, the secondfractionation zone produces the one or more C20-C40 hydrocarbons stream.

The embodiments disclosed herein provide an efficient and economicalmechanism for an improved conversion process. Particularly, a thermalcracking heater can process at least a portion of product from a slurryhydrocracking apparatus. By thermally cracking a recovered LVGO andoptionally an HVGO stream, these materials can be converted to gasolineand diesel. Hence, the overall operation of an apparatus can be improvedgreatly.

DEFINITIONS

As used herein, the term “stream” can include various hydrocarbonmolecules, such as straight-chain, branched, or cyclic alkanes, alkenes,alkadienes, and alkynes, and optionally other substances, such as gases,e.g., hydrogen, or impurities, such as heavy metals, and sulfur andnitrogen compounds. The stream can also include aromatic andnon-aromatic hydrocarbons. Moreover, the hydrocarbon molecules may beabbreviated C1, C2, C3 . . . Cn where “n” represents the number ofcarbon atoms in the one or more hydrocarbon molecules. Furthermore, asuperscript “+” or “−” may be used with an abbreviated one or morehydrocarbons notation, e.g., C3⁺or C3⁻, which is inclusive of theabbreviated one or more hydrocarbons. As an example, the abbreviation“C3⁺” means one or more hydrocarbon molecules of three carbon atomsand/or more.

As used herein, the term “zone” can refer to an area including one ormore equipment items and/or one or more sub-zones. Equipment items caninclude one or more reactors or reactor vessels, heaters, exchangers,pipes, pumps, compressors, and controllers. Additionally, an equipmentitem, such as a reactor, dryer, or vessel, can further include one ormore zones or sub-zones.

As used herein, the term “atmospheric equivalent boiling point” may beabbreviated “AEBP” and calculated by ASTM D1 160-06 as disclosed in US2010/0326882.

As used herein, the term “naphtha” can refer to one or more C5-C12hydrocarbons and may have an AEBP of about 85-about 190° C.

As used herein, the term “diesel” can refer to one or more C8-C21hydrocarbons and may have an AEBP of about 150-about 400° C.

As used herein, the term “vacuum gas oil” may be abbreviated “VGO”, caninclude one or more C20-C50 hydrocarbons, and may have an AEBP of about300-about 580° C.

As used herein, the term “light vacuum gas oil” can be abbreviated“LVGO”, can include one or more C20-C40 hydrocarbons, and can have anAEBP of about 300-about 490° C.

As used herein, the term “heavy vacuum gas oil” may be abbreviated“HVGO”, can include one or more C30-C50 hydrocarbons, and may have anAEBP of about 370-about 580° C.

As used herein, the term “vacuum residue” may be abbreviated “VR”, caninclude one or more C40⁺hydrocarbons, and may have an AEBP of at leastabout 510° C. Moreover, the term “vacuum residue” may be usedinterchangeably with the term “pitch”.

As used herein, the term “vapor” can mean a gas or a dispersion that mayinclude or consist of one or more hydrocarbons.

As used herein, the term “overhead stream” can mean a stream withdrawnat or near a top of a vessel, typically a distillation column or flashdrum.

As used herein, the term “bottom stream” can mean a stream withdrawn ator near a bottom of a vessel, typically a distillation column or flashdrum.

As depicted, process flow lines in the FIGURE can be referred tointerchangeably as, e.g., lines, pipes, feeds, products, parts,portions, or streams.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE is a schematic depiction of an exemplary heavy hydrocarbonprocessing apparatus.

DETAILED DESCRIPTION

Referring to the FIGURE, an exemplary heavy hydrocarbon processingapparatus 100 can include a hydrocracking reaction zone 120, a flashzone 200, a first fractionation zone 300, a second fractionation zone400, and a thermal cracking heating zone 500. Generally, a hydrocarbonfeed 80 can include VR and/or atmospheric bottoms and be optionallycombined with a portion of the recycle HVGO stream 452, as hereinafterdescribed. A combined hydrocarbon feed 84 can optionally receive aparticulate catalyst in a line 60 to form a well-mixed homogenoushydrocarbon and catalyst stream 86.

Useful particulate catalyst can include ferrous sulfate, such as ironsulfate monohydrate, having particle sizes of no more than about 45 μ m,or a bauxite catalyst. Exemplary particulate catalyst is disclosed in,e.g., U.S. Pat. No. 4,963,247. Optionally, coke-inhibiting catalystparticles and/or oil soluble coke-inhibiting additives may be used, asdisclosed in, e.g., US 2010/0326887. Generally, the particulate catalystis not regenerated.

A hydrogen stream 40 may optionally be combined with another portion 272of the recycle stream 264, as hereinafter described, to form a hydrogenstream 274. The hydrogen stream 274 can be split into a hydrogen streampart 276 and a feed hydrogen stream 44. The feed hydrogen stream 44 canbe added to the combined hydrocarbon and catalyst stream 86 to form ahydrogen, one or more hydrocarbons, and catalyst or feed stream 88.Generally, the feed stream 88 contains an effective amount of hydrogento undergo a hydrocracking reaction.

A feed heater 90 and a hydrogen heater 92 can receive, respectively, thefeed stream 88 and the hydrogen stream part 276. These streams can beheated to the appropriate temperature to create a heated hydrogen stream278 and a reactor feed stream 94. The streams 94 and 278 can be providedto the hydrocracking reaction zone 120. Thus, the feed streams enteringthe hydrocracking reaction zone 120 can include solid catalyst, liquidhydrocarbons, and gaseous hydrogen and hydrocarbons.

The hydrocracking reaction zone 120 can include a slurry hydrocrackingreactor 130. The slurry hydrocracking reactor 130 can receive thestreams 94 and 278 via any suitable distributor to provide ahydrocracked stream 140. The hydrocracking reaction zone 120 can beoperated at a pressure of about 3.5-about 24 MPa, a temperature of about350-600° C., preferably about 400-about 500° C. The liquid hourly spacevelocity may be below about 4 hr⁻¹, preferably about 0.1-about 3 hr⁻¹,on a fresh feed basis. The per-pass VR conversion may be about 50-about95%, by weight. The hydrogen feed rate can be about 670-about 3,300Nm³/m³ oil. Although the hydrocracking reaction zone 120 can include avariety of known reactors of either up or downflow, it is particularlywell suited to a tubular reactor through which feed and gas move upward.Hence, an outlet from the slurry hydrocracking reactor 130 is above aninlet. Optionally, antifoaming agents, such as silicones, may beprovided. Although only one is shown in the FIGURE, one or more slurryhydrocracking reactors may be utilized in parallel or in series toconvert at least a portion of the liquid feed to a gas and/or adispersion product.

The hydrocracked stream 140 can optionally receive a portion 270 of therecycle stream 264 as a quench, as hereinafter described, and beprovided to the flash zone 200 prior to sending to the firstfractionation zone 300. The flash zone 200 can include one or moreseparation vessels, such as a high pressure separator 220, a hot flashdrum 240, a cold high pressure separator 260, and a cold flash drum 280.

The hydrocracked stream 140, which may be a mixture of gases andliquids, can be provided to the high pressure separator 220. The highpressure separator 220 may be operated at a temperature of about200-about 500° C., and a pressure of about 3.5-about 24 MPa. The highpressure separator 220 can provide an overhead stream 224, includingprimarily gases, and a bottom stream 226, including primarily liquids.The overhead stream 224, optionally cooled by a cooling water exchanger,can be received by the cold high pressure separator 260.

The cold high pressure separator 260 can be operated at a temperature ofabout 10-about 100° C., and a pressure of about 3.5-about 24 MPa. Thecold high pressure separator 260 can provide a recycle stream 264including primarily hydrogen with impurities such as ammonia, hydrogensulfide, and light hydrocarbons, and a bottom stream 266. Optionally,the recycle stream 264 may be scrubbed after exiting the cold highpressure separator 260, and used elsewhere in a refinery or a chemicalmanufacturing plant, or recycled as described below.

In one exemplary embodiment, the recycle stream 264 can be split into arecycle stream portion 270 and another recycle stream portion 272. Theportion 270 can be combined with the hydrocracked stream 140, asdescribed above. Another portion 272 of the recycle stream 264 can becombined with the hydrogen stream 40 to form a combined hydrogen stream274. This combined hydrogen stream 274 may be split into the streams 276and 44 that can be heated or combined with the feed, as described above.Generally, the recycling of the stream 264 is optional including theprovision of the stream 44 into the stream 86 and the hydrocrackedstream 140. If the stream 264 is not recycled, the hydrogen stream 40can be provided directly to the stream 86 or the slurry hydrocrackingreactor 130.

The bottom stream 266 of the cold high pressure separator 260 can becombined with an overhead stream 244. Particularly, the high pressureseparator 220 can provide the bottom stream 226 to the hot flash drum240. The hot flash drum 240 may be operated at a temperature of about200-about 500° C., and a pressure of about 0.7-about 3.5 MPa. The hotflash drum 240 can provide the overhead stream 244 and a bottom stream246. The overhead stream 244 can be combined with the bottom stream 266to form a combined stream 268. The combined stream 268 can be providedto the cold flash drum 280. The cold flash drum 280 can provide anoverhead stream 284, including a fuel gas having one or more C4⁻hydrocarbons, and a bottom stream 288. The bottom streams 246 and 288can be provided to the first fractionation zone 300.

The first fractionation zone 300 can include an atmosphericfractionation column 310. The atmospheric fractionation column 310 canreceive the streams 246 and 288. Generally, the atmosphericfractionation column 310 may be operated at any suitable conditions toprovide one or more C4⁻ hydrocarbons stream 320, one or more C5-C12hydrocarbons stream 340, which may be referred to as a naphtha stream,one or more C8-C21 hydrocarbons stream 360, which may be referred to asa diesel stream, and one or more C20-C50 hydrocarbons stream 380, whichmay be referred to as a VGO stream. Optionally, medium pressure steammay be provided near the bottom of the atmospheric fractionation column310 to strip lighter components from heavier components. The streams320, 340, and 360 may be recovered and provided to their respectiveproduct pools.

The one or more C20-C50 hydrocarbon stream 380 can be optionallycombined with a hydrocarbon stream 384, which typically includes heavierhydrocarbons, such as VGO. These heavier hydrocarbons can be recoveredfrom other units within the refinery or chemical manufacturing plant.The streams 380 and 384 can be provided to a vacuum charge heater 390 toprovide a heated feed stream 394. Usually, the heated feed stream 394 isheated to a temperature of no more than about 370° C.

The heated feed stream 394 can then be sent to the second fractionationzone 400. The second fractionation zone 400 can include a vacuumfractionation column 410. The vacuum fractionation column 410 may beoperated at a pressure of about 1-about 10 kPa, preferably about 1-about7 kPa and at a vacuum distillation temperature resulting in anatmospheric equivalent cut point of LVGO and HVGO of about 370-about490° C., preferably about 390-about 460° C. The vacuum fractionationcolumn 410 can utilize any suitable equipment for maintaining a vacuum,such as a three-stage educator or a line providing stripping steam. Thevacuum fractionation column 410 can provide an overhead stream 416, oneor more C20-C40 hydrocarbons stream or LVGO stream 420, optionally oneor more C30-C50 hydrocarbons stream or HVGO stream 440, and one or moreC40⁺hydrocarbons stream or pitch stream 460. A portion of the pitchstream 460 can optionally be recycled to the hydrocracking reaction zone120. Exemplary hydrocracking reaction zones, flash zones, firstfractionation zones, and second fractionation zones are disclosed in,e.g., US 2010/0326882, US 2010/0326887 and US 2010/0329935.

The one or more C20-C40 hydrocarbons stream 420 can optionally becombined with a portion 448. Particularly the one or more C30-C50hydrocarbons stream or HVGO 440 can be split into an optional HVGOproduct stream 444, a thermal cracking zone feed stream 448, and arecycle HVGO stream 452. Thus, the HVGO stream 440 can be split into twoor more streams with a third option of recovering an HVGO product.Moreover, a portion 452 of the HVGO stream 440 can be combined with thefeed 80 to be reprocessed through the hydrocracking reaction zone 120.The LVGO stream 420 can be combined with the stream 448 to form a chargestream 456. This charge stream 456 can be provided to the thermalcracking heating zone 500 and be at least a portion of the hydrocrackedstream 140. This charge stream 456 can include at least one of an LVGOand an HVGO. The charge stream 456 can then be sent to the thermalcracking heating zone 500. In addition, the charge stream 456 canreceive a diluting stream 520, such as steam.

The thermal cracking heating zone 500 can operate at conditionseffective for thermal cracking Generally, the thermal cracking heatingzone 500 can include a thermal cracking heater 510. The thermal crackingheater 510 can operate at a temperature of about 300-about 550° C.,preferably about 450-about 500° C., with a residence time of about10-about 400 minutes, preferably about 60-about 120 minutes. Typically,the pressure employed results in a liquid phase operation, but gases mayalso be present. The pressure can be from about 170-about 10,450 kPa,preferably about 1,480-about 7,000 kPa.

After passing through the thermal cracking heater 510, a product stream530 from the thermal cracking heating zone 500 can be provided to thefirst fractionation zone 300 for separating desired products, such asgasoline and diesel. An exemplary thermal cracking heater 510 isdisclosed in, e.g., U.S. Pat. No. 4,892,644.

Thus, the embodiments provided herein can allow the thermal cracking ofLVGO to produce additional valued products. Particularly, increasedproduction of naphtha and/or diesel can be obtained while providing anefficient and economical improvement to a slurry hydrocracking zone.

Without further elaboration, it is believed that one skilled in the artcan, using the preceding description, utilize the present invention toits fullest extent. The preceding preferred specific embodiments are,therefore, to be construed as merely illustrative, and not limitative ofthe remainder of the disclosure in any way whatsoever.

In the foregoing, all temperatures are set forth in degrees Celsius and,all parts and percentages are by weight, unless otherwise indicated.

From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of this invention and, withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various usages andconditions.

The invention claimed is:
 1. An apparatus for thermal cracking one ormore hydrocarbons, comprising: A) a slurry hydrocracking zone forreceiving a hydrocarbon feed and a particulate catalyst; B) a firstfractionation zone for receiving a hydrocracked stream from the slurryhydrocracking zone; C) a second fractionation zone for receiving a oneor more C₂₀-C₅₀ hydrocarbons stream from the first fractionation zonewherein the second fractionation zone produces a one or more C₂₀-C₄₀hydrocarbons stream; and D) a thermal cracking heating zone forreceiving the one or more C₂₀-C₄₀ hydrocarbons stream.
 2. The apparatusaccording to claim 1, further comprising a flash zone for receiving thehydrocracked stream prior to sending to the first fractionation zone. 3.The apparatus according to claim 1, wherein the first fractionation zonecomprises an atmospheric fractionation column and the secondfractionation zone comprises a vacuum fractionation column.